In the field of digital photography the term full well capacity can be defined as the maximum signal or number of electrons that each pixel can hold before saturating. This has an effect on dynamic range of image sensor.
One of the decisions that has to be made when designing an image sensor is the trade off between full well capacity, performance in low light conditions (conversion gain: how high signal voltage each electron generates) and density of defect pixels. The higher voltage is applied to a pixel, the higher full well capacity can be achieved. However, higher voltage may increase the defect density of the pixels.